On Mon, 05 Nov 2018 15:14:02 +0000, BenTenBox wrote:

replying to harry, BenTenBox wrote:
many thanks for all the replies, I'll measure the joist length when I
get home, there are several walls directly below, the main wall running
along the middle of the top floor, presumably I should measure from that
wall the end eaves?

Make sure the walls are all supporting walls.

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